Category: Press

On Jan 17, NBA Hall of Famer, one of “50 Greatest Players in NBA History,” and iconic Deadhead Bill Walton came to town to be the color commentator for the UA-Oregon men’s basketball game. Whenever Walton is a commentator ESPN has a 2-minute feature called “Walton’s World.” In this episode, Bill visited the MagAO-X lab at Steward!

During our recent observing run we tested a new set of coronagraphs (devices for blocking star light so we can see planets!), which were developed by our friends Gilles Otten, Frans Snik, and Matt Kenworthy at Leiden University, in the Netherlands. Today Gilles gave a talk at the Spirit of Lyot Conference in Montreal, Canada. The new coronagraphs work spectacularly well! You can read about these results in Dutch, French, and in English.

Here is our announcement of this great news:

Astronomers develop breakthrough optical component for detecting exoplanets close to their host stars

Astronomers from Leiden University (the Netherlands) and the University of Arizona (USA) have successfully commissioned a new type of optic that can reveal the image of an exoplanet next to its parent star. The ‘vector Apodizing Phase Plate’ (vector-APP) coronagraph was installed at the 6.5-m Magellan Clay telescope in Chile in May 2015, and the first observations demonstrated an unprecedented contrast performance very close to the star, where planets are more likely to reside. These results will be presented by PhD student Gilles Otten (Leiden) this Monday to the scientific community at the “Spirit of Lyot” conference in Montreal.

Almost 2000 exoplanets have been detected to date, but only a handful of those have been imaged directly. Exoplanets are typically more than a million times fainter than and are lost in the glare of their parent star as seen from Earth. To directly image exoplanets and to characterize their atmospheres, astronomical instruments at the world’s largest telescopes use coronagraphs to suppress the overwhelming halo of light from the star.
The vector-APP coronagraph[1] uses the wavelike nature of light to cancel out the starlight whilst allowing the planet’s light to shine through.

This manipulation is implemented through a complex phase pattern that can only be manufactured using advanced liquid crystal 3D patterning techniques [2]. This technique creates two images of the star, for which dark D-shaped regions are located on opposite sides of each star image (see Figure 1). In this way, the whole region around the star can be scrutinized for planets. By combining several layers of liquid crystals, the device can be used over a wide range of wavelengths, including the infrared where the contrast between planet and star is more favorable.

On May 6, 2015 a vector-APP coronagraphic device saw first light (at 3.9 um wavelength, in the infrared range of the spectrum) at the MagAO[3] instrument, attached to the 6.5-m diameter Magellan Clay telescope in Chile. The telescope’s integrated adaptive optics system provided the instrument with sharp images of stars, which were consequently split up and modified by the coronagraph to exhibit dark holes in which much fainter planets could be imaged than without the vector-APP coronagraph.

Figure 1: Double image of the star Eta Crucis taken through the vector-APP coronagraph installed at MagAO. The two main images of the star exhibit D-shaped dark holes on complementary sides. Coronagraphic phase pattern designed by Christoph Keller (Leiden). Credit Leiden University, University of Arizona

Frans Snik (Leiden University), who invented the principle behind the new vector-APP coronagraph, says: “It is fantastic to see that after all our design work and lab testing, this new approach works perfectly at the telescope on the very first night!” Gilles Otten adds: “We knew that we were in business as soon as we saw the first picture on the screen in the telescope control room.”

Figure 2: Double image of the star beta Centauri taken through an experimental version of the vector-APP coronagraph installed at MagAO. Both images of the star contain a dark region that covers the complete 360 degrees around the central star. In both cases, the binary companion to beta Centauri is easily detected. Coronagraphic phase pattern designed by Christoph Keller (Leiden). Credit Leiden University, University of Arizona.

Jared Males (NASA Sagan Fellow, University of Arizona) is excited about the opportunities of the vector-APP: “With this new coronagraph we are now looking for planets around nearby stars. We have the capacity to directly detect, or rule out, planets smaller than Jupiter. ” Matthew Kenworthy (Leiden) concludes: “This new coronagraph technology is also excellent news for the extremely large telescopes currently under construction. With a vector-APP coronagraph in the next generation of telescopes, we can search for planets around nearby stars with unprecedented sensitivity.”

The advanced liquid crystal technology that the team adopted also permitted the production of extreme vector-APP designs that are not possible with more traditional manufacturing technologies. These new designs produce dark holes that cover the full 360 degrees around the target stars. The first data from an experimental device already shows the viability of this novel approach (see Figure 2).

Support from the William F. and Elizabeth Lucas Junior Faculty Astronomy Award and the NASA Origins of Solar Systems program made this exciting commissioning possible at the MagAO instrument in Chile. This work was performed in part under contract with the California Institute of Technology (Caltech) funded by NASA through the Sagan Fellowship Program executed by the NASA Exoplanet Science Institute.

[1] For an introduction to the principles behind the vector-APP coronagraph, see Snik et al. (2012) and Otten el al. (2014). The name “vector-APP” stems from “Apodizing Phase Plate” based on polarization (vector) techniques. The original optical theory was developed by Johanan Codona at the University of Arizona.

[2] The vector-APP coronagraph devices for MagAO were developed in collaboration with the group of Dr. Michael Escuti at North Carolina State University, and were produced by ImagineOptix.

Welcome APOD and Sky and Telescope readers. This post was written while MagAO was mounted on the Clay 6.5 m telescope, and we post daily updates throughout the run on the main page. You can also find out about some of our scientific results using the In The News and Results pages.

You can also read about our eyepiece observations in a post by Tom Beal at the Arizona Daily Star.

On our first night on-sky in 2015A, our infrared camera Clio wasn’t quite ready to mount on the telescope. We also needed to test operating the AO system with a different camera, since there are several new instrument concepts in the works (Clio’s entrance window is the dichroic which sends light to the Pyramid and VisAO). The result of these fortunate circumstances is that we mounted the eyepiece for the very first time.

Laird presents the MagAO eyepiece. It is mounted where Clio normally goes.

The night started out poorly. It was cloudy, a guider communications cable failed deep inside the telescope, and one of VisAO’s hard drives failed.

Our first night started out cloudy. (Picture by Yuri Beletsky, click for larger image)

The telescope staff went to work on the cable, and Jared tore apart the VisAO electronics. Meanwhile, Laird was doing some last minute alignment checks on the eyepiece. At around midnight, all the problems were fixed and the sky magically began to clear.

Once we opened, we immediately pointed at alpha Centauri A which is a very bright star and so makes a good alignment target. Working out on the platform in near freezing temperatures, we moved the MagAO Pyramid wavefront sensor around until it was aligned to the star with the eyepiece dichroic.

Eyepiece alignment was done on the platform. At left is a cellphone image of alpha Cen A&B imaged on a card through the eyepiece. At right is the simultaneous image on the VisAO camera (on a laptop screen on the platform). These are open-loop images (before we turned on the AO).

Then, on the first try, we closed the loop at 1000 Hz controlling 300 modes.

Proof that the loop was closed while we were observing.

At that point, we were observing the alpha Centauri system at the diffraction limit of a 6.5 meter telescope! Luckily the moon was out, giving Yuri Beletsky plenty of light to document the whole thing.

Laird Close, the MagAO PI, observes alpha Cen at the diffraction limit of the 6.5 meter Clay telescope. The inset shows an image recorded with VisAO, MagAO’s visible wavelength science camera, at nearly the same wavelength (i’). Reports from all observers indicate that it looks just like this through the eyepiece! (Photo by Yuri Beletsky, click for larger image)

The eyepiece had a very red filter installed, passing wavelengths longer than 685 nm. This means the sharpest details in the image were as small as 22 milli-arcseconds. We’re pretty sure that this is the highest angular resolution image ever formed on a human retina. We compared what we saw to images recorded on the VisAO science camera at nearly the same wavelength, and it was very gratifying to see the similarities.

Katie tried her hand at drawing the image. You can see the 22-milliarcsecond core of A, the control radius around A, the chromatically elongated speckles, some atmospheric dispersion is evident, and you can see that anisoplanatism is affecting the image of B.

Jared, Katie, and Laird pose next to the eyepiece. Katie is holding The Book. (Photo by Yuri Beletsky, click for bigger version)

During the night, 9 people looked through the eyepiece. These astronomers are the inaugural members of an exclusive club: “L’Ordine degli Astronomi al Limite di Diffrazione” (The Order of Astronomers at the Limit of Diffraction). In this moonlit timelapse you can see most of them take their turn.